Electrical testing device.



G. A. HETH-BRINGTON. ELECTRICAL TESTING DEVICE. APPLICATION FILED 1120.20, 1909.

988,192 I Patented Mar. 28, 1911.

UNITED strA'rEs fgjrnucr oFFioE CHARLES A. HETHEBINGTON, OF DES MOINES, IOWA.

ELECTRICAL TESTING DEVICE. I

Patented Mar. 28, 1911.

988,192. Specification of Letters Patent.

' Application filed-December 20, 1909. Serial No. 534,196.

To all whom it may concern:

Be it known that I, CHARLES A. Hernan- INGTON, a citizen of the United States, residing at Des Moines, in the county of Polk and purpose of determining whether ornot the State of Iowa, have invented a certain new and useful Electrical 'lestin Device, of which the following is a specification.

The object of my invention is to provide a screw driver having contained in the handle thereof an electrical testing device whereby the operator may apply the device to two adjacent electric terminals for the said wires are electrically charged, and further to provide a device of this kind that is adapted to be-used for testing currents of materially difierent voltage by the use of some incandescent lamp without injury to the lamp such as would be caused by the use of a current of high voltage on the lampadapted to be lighted by a current of comparatively low voltage; and further to provide a screw driver of this kind in which the blade may be readily and easily detached and another one substituted therefor while maintaininga good electric contact between the blade and the resistance coils.

of Fig. 1, andFig. 4 shows a sectional view on the line 44 of Fig. 1.

Referring to the accompanying drawings, I have used the reference numeral 10 to indicate the body of the screw driver handle which is made of insulating material and which is formed with a central recess 11.-

At the rear end of the handle 10 is a screw cap 12 which may be made of metal and which is provided with a glass 13 through whichthe incandescent lamp on the interior of the screw cap 12 may be seen. At the rear of the recess 11 in the handle is a hinged insulated door 14 that may be held in closed position by a hook 15 and which is provided at its central portion with a socket 16 in which an incandescent lamp 17 is placed.

Contained within the. recess 11 of the handle is a metal rod 18 having an insulator spool 19 thereon. Connected with one end of the rod 18 is a conductor 20 electrically connected with the lamp 17 and wound upon the said insulator'spool is a'resistance coil 21 having one end electrically connected with the lamp socket by means of the conductor 22. This coil has attached to it three terminals; the first one indicated by the numeral 23 being at the end farthest from the left; the second one 24 being about the center of the coil and the third, 25 being connected direct to the conductor 22. Connected with each of these terminals 23, 24 and 25 is a I the handle, I have provided a locking pin 31 having a notch 32 designed to receive one corner of the squared end of the screw driver blade. In one corner of the screw driver blade is a notch as illustrated in Fig. 1 to receive the pin 31 and said pin 31 is normally held outwardly so that the notch 32 will be away from the corner of the screw driver blade by means of the spring 33. I have also providedfor limiting the outward movement of the pin 31 by means of a small pin 34 seated in the handle and inserted in a slot 35 in the pin 31.

In practice if it is desired to remove the screw driver blade the operator first presses the pin 31 inwardly until its notch 32 is 111 line with the corner of the screw driver, whereupon the screw driver blade may be removed.

In Fig. 1 of the drawings, I have illustrated an object 36 having two electric terminals 37 and 38 thereon. In practical use with an electric circuit of, say for instance,

two hundred and twenty volts, and assuming that he desires .to test two adjacent terminals to determine whether or not the wires are electrically charged he then places the one terminal 38 in contact with the terminal stance, the current With which the operator is working is of one hundred and ten volts, then the terminal 38 is app'liedto the terminal wire 24: and the resistance between the terminal wire 24 and the lamp is so arranged that the current will cause the lamp to burn in a normal manner. If, for instance, the current with which the operator is working is of comparatively low voltage such, for instance, as is usually found in an electric bell circuit, then the operator places the terminal 38in contact with the terminal wire 25 and then the current goes direct to the lamp without going through the resistance wire. By this arrangement it is ob vious that a single lamp adapted for use with low voltage may be used for indicating to the operator the presence or absence of a current in the wires with which he is working. Furthermore by having the screw driver blade arranged to form one of the -terminals for the testing instrument it is obvious that the'operator may readily and easily test the current of two wires adjacent to each other or two terminals that are spaced apart at different distances. Furthermore by applying a device of this kind to a screw driver which is an instrument that must be used by electric operators quite frequently the operator will always have at hand atesting instrument, and furthermore by carrying a number of blades 27 of different sizes they may be readily and easily substituted so that the operator need only carry one handle and testing instrument for use in connection with any ordinary work in'which he may be employed.

Access may be had to the lamp readily and easily by simply unscrewing the screw cap .12, and access may be had to the coil by swinging the hinged door 14 to an open posltlen.

I claim as my invention: 1. In a device of the class described, the combination of a screw driver handle formed of insulating material and having a recess on its interior, a screw driver blade connected therewith, a resistance coilccontained within the handle, a series of terminal wires connected with the coil at points spaced} apart, an electric lamp contained within the handle, and means for electrically connecting the lamp at one side with the coil and at its other side withthe screw driver blade, and means for detachably securing the'screw driver blade to the handle.

2. In a device of the class described, the combination of a screw driver handle made of insulating material and having a recess therein, a metal rod in the screw driver handle contained in said recess, a screw driver blade inserted in the handle, a spring pressed rod in the screw driver blade designed to engage the rod-in the handle, means for locking the screw driver blade in posi- 'tion within the handle, a resistance coil wound upon the rod within the recess, a number of terminal wires connected to said resistance coil at points spaced apart from each other, an electric lamp contained within the handle, means for connecting the resistance coil within oneside of the lamp, and means for connecting'the otherside-of the lamp with the rod within said recess.

3. A device of the class described, comprising a screw driver handle made of insulating material and having a recess therein, and also being open at its end, a hinged door made of insulating material to cover said opening, an electric lamp socket in said door, an electric lamp in said socket, a screw cap on the'end of the handle to cover sa d lamp, said cap having an opening therein through which the lamp may be seen, a rod arranged in said recess, an insulator on sa1d rod, a resistance coil wound upon the insulator, means for electrically connectmg the resistance coil at one end with the lamp socket, means for electrically connecting the I rod with the lamp, a series of terminal w res connected'to the resistance coil, the termmal plates arranged in the side of the handle in contact with said terminal wires, a detachable screw driver blade in the handle, means for locking it in position, a spring pressed rod within the screw driver blade, said rod being with the rod on which the coil is supported,

" substantially as set forth.

Des Moines, Iowa, Dec. 6, 1909.

CHARLES A. HETHERINGTON. Witnesses:

- M. B. GOLDIZEN, M. WALLACE.

designed to be held in engagement 

